The present invention relates to a display device in which a positive image film is back illuminated, such as a display panel including a light guiding plate at the forefront thereof. This display device includes a light source unit housing a fluorescent light source in a closed space of a housing, a large number of light guiding panels disposed over the upper surface of said light source unit, and a reflection panel disposed on the back surfaces of the light guiding panels. The light of the fluorescent light source is transmitted from the light incident end surface to the light guiding panel. Due to light guidance according to the light guiding pattern formed on the light guiding panel, a positive print film, disposed on the front surface, is back-illuminated as uniformly as possible and with high brightness. One such display panel is disclosed in Japanese Patent Publication No. 2623028.
The above-mentioned example can function effectively as a display device for advertisement and decoration. However, the housing for the fluorescent lamp is relatively thick and the use of multiple light guiding panels leads to further thickening the housing. As a result, the structure thereof becomes complicated. Moreover, this type of display device is suitable for a stand-alone type display device but it is undesirable for wall-mounting display devices because the housing protrudes from the front/rear side.